The bodies were found by police who broke down the door to the address on April 15, about 36 hours after they died.

The jury heard how the boy had four knives in a backpack, including a large black-handled kitchen knife which was shown to jurors.

The prosecution barrister said that the boy had then gone into one of the bedrooms where he "pinned Mrs Edwards down on the bed by kneeling astride her".

Inside the house, officers discovered a large kitchen knife in one of the bedrooms.

The court was told the pair watched several episodes of Twilight together before they were arrested.

They sat emotionless in the dock as the details of the case were outlined to a jury and a public gallery packed full of relatives who wept during proceedings.

Both teenagers were arrested shortly after officers made the grim discovery.

SWNS

POPULAR: Elizabeth was a 'well respected' dinner-lady

Tragic Ms Edwards worked as a dinner lady at St Paul's Community Primary School and Nursery in Spalding.

Colleagues described her as a "very well-respected member of our staff."

The killing sent shockwaves through the local community, who paid tribute to Elizabeth and Katie.

Lucy Nelson, 32, who lives on an adjacent street to the small cul-de-sac where they lived, said at the time: "It is an absolute tragedy and I hope they can now rest in peace.

"They were a quiet family as far as I know, you never heard of any trouble from them."

SWNS

DEVASTATED: Elizabeth's partner Graham Green appeared in court

Her eldest daughter Mary Cottingham wrote on Facebook at the time: "I'm still in shock, can't believe they are gone. I love them so much, I need my mum.'The 27-year-old added: 'Gone too soon but will never be forgotten. I love you both."